抄録

Since 2000, our department has been calculating the percent injected dose (%ID ; the accumulation ratio of an injected amount) in isolated lymph nodes when detecting sentinel node navigation surgery for upper gastrointestinal tract cancers. However, the conventional procedure of calculating %ID is complicated. In this study, we used DCM-200 (Aloka Co., Tokyo, Japan). This is equipped with two wells, one to receive a syringe to measure high-level radioactivity, and one for insertion of a tube to measure low-level radioactivity. We compared results using the conventional autowell method and the DCM method. (Subjects and Methods) Ten patients with T1N0 gastric cancer underwent SNNS using the RI method. The radioactivity of 54 lymph nodes was measured using both a well-type scintillation counter ARC-300 and the DCM-200. Each gross count and %ID, which was obtained using the conventional calculation method and the DCM-200 method, were compared. (Results) The gross counts among the instruments showed a high correlation (r=0.960). The calculated %ID showed a high correlation, with the value found by the DCM-200, being approximately 1.5 times higher than that found using the conventional calculation method. (Conclusion) The DCM-200 allowed both the administered amount and the amount found in the isolated lymph node to be measured with high sensitivity. Correction for radioactive decay as a factor of time is performed automatically, so that both conversion between instruments and correction for decay over time can be omitted, resulting in a simple calculation process.